#include <stdio.h>
#include <string.h>
#include <math.h>

main()
{
	double x,y,c;
	double mid;
	double an;
	double left, right;
	double fen1,fen2;
	double va;
	while (scanf("%lf%lf%lf", &x, &y, &c)!=EOF)
	{
		left=0;
		right=x<y? x:y;
		while (left<right)
		{
			mid=(left+right)/2;
			fen1=sqrt(x*x-mid*mid);
			fen2=sqrt(y*y-mid*mid);
			va=c/fen1+c/fen2;


			if (fabs(va-1)<1e-8)
			{
				break;
			}
			else if (va<1)
			{
				left=mid;
			}
			else
			{
				right=mid;
			}			
		}
		printf("%.3lf\n",mid);
	}

	return 0;
}